PTGDS and pulmonary arterial hypertension: Consistent with our scRNA-seq data, the analysis of the HUCMSC-CM prostaglandins detected a major PGE2 signal but only minimal levels of PGF2α (Fig. 2b) and absent PGD2, altogether suggesting that HUCMSC-CM-secreted PGE2 may contribute to the beneficial effect of the HUCMSC-CM on our PAH patient.